first of all, let me say that I would have really big problems choosing who's the best texturer between me, you, venom or tomcat, thought we have completely different styles.
But considering that you already are an excellent texture artist, I always feel a bit ...
... when you say you don't use layers or other important tools...you obviously already achieve an astonishing level without them...so...what could you do with a more extended use of them?
I know that many photoshop options are there mostly to speed up things rather than obtaining better results but, in my opinion, they still would probably let you go beyond your actual level.
I don't say you should change your style (wich you are more comfortable with, and that you find more suitable for your objectives), I just say that it could be enriched.
A stupid example: I know at least 4 or 5 different methods to make a ruined painted line like this one:
but from my experience the best quality result (and the fastest one too) can be obtained only using at least 2 different layers and a layer mask. You can do almost the same with only handdrawing on a sinlge layer, but why you should if there is another way better and faster?
About the bevel, yes you are right, I had too the problem of wrong light direction with flipped faces, sometimes you can use some strategies to avoid or reduce it, some other times you have to give up the simmetry (and make two versions of the reversed areas), but consider also that human eyes, when there are illusions (and bevel is an illusion) will render the illusion coherently with the contest: this mean that often, althought the light is wrong, observers will have to force themselves to see a bevel direction coherent with the light instead of with the other parts, althought I admit it is better to avoid those situations.
Example: in this image the light direction of the bevel is a bit screwed (I already changed it a little), nonetheless you have to force yourself to view the opposite bevel on the flipped faces.
